124 F. F. Fritsch and E. J. Salisbury. 
Attention may be drawn to the fact that series 2, 4 and 6 in 
Table III were obtained amongst some of the tallest heather on the 
area and that these exhibit a much more pronounced difference 
between the average daily and the average total evaporation at the 
ground-level than the series 1, 3 and 5 and those in Table IV. As 
a matter of fact the evaporation at night on the ground, in Calluna 
over three feet high, is only about one-third of that in the CUE 
facies where the Calluna is about one foot high (see also Table V). 
This shows that the soil of the former is subjected to considerably 
less desiccation. 
Evaporation is, however, a much more potent factor after all 
shelter has been removed by fire, as shown in Table V. From this 
it is apparent that evaporation at the ground-level is more than 
doubled after burning (cf. Table III). In Table V, the first two 
series of readings were taken on hot sunny days, whereas series 3-5 
were obtained on dull windy days. It will be noted that in the 
former set of readings the evaporation at the 3 ft. level is lower than 
at 18 ins., a feature which is not apparent in the latter. Moreover, 
in all the series, night readings in general show little difference as 
between the 18 in. and the 3 ft. levels. These results point to rad¬ 
iation from the bare ground being an important factor at levels not 
far above the surface. 
TABLE V. 
Evaporation (in Cubic Centimetres) on Burnt Areas. 
Ground. 
18 ins. 
3 FT. 
Series 1 
(av. daily 
3-69 
4-21 
3-34 
(F 3 on slope) 
(av. total 
3-27 
3-45 
• . • 
3*37 
Series 2 
(F 3 near top 
of slope) 
(av. daily 
|av. total 
2-66 
2-47 
3-97 
3-26 
• • • 
304 
2-67 
Series 3 
( F 2 top of | 
slope) 
av. daily 
av. total 
2-18 
1*68 
2-42 
1-68 
• • • 
2-91 
2-08 
Series 4 . 
(F 2 half way 
down slope) 
av. daily 
av. total 
2-29 
1-66 
2-88 
2-10 
• • • 
302 
217 
Series 5 
(F 2 base of ' 
slope) 
av. daily 
av. total 
1-97 
1*39 
2-65 
1-90 
2-92 
211 
Average daily 
for all 
series 
... 
2-56 
3-22 
• • » 
305 
